Re: [PATCH v19 039/130] KVM: TDX: initialize VM with TDX specific parameters

[Juergen Gross]

On 17.05.24 16:32, Kirill A. Shutemov wrote:
> On Mon, Feb 26, 2024 at 12:25:41AM -0800, isaku.yamahata@xxxxxxxxx wrote:
> > @@ -725,6 +967,17 @@ static int __init tdx_module_setup(void)
> >   
> >   	tdx_info->nr_tdcs_pages = tdcs_base_size / PAGE_SIZE;
> >   
> > +	/*
> > +	 * Make TDH.VP.ENTER preserve RBP so that the stack unwinder
> > +	 * always work around it.  Query the feature.
> > +	 */
> > +	if (!(tdx_info->features0 & MD_FIELD_ID_FEATURES0_NO_RBP_MOD) &&
> > +	    !IS_ENABLED(CONFIG_FRAME_POINTER)) {
>
> I think it supposed to be IS_ENABLED(CONFIG_FRAME_POINTER). "!" shouldn't
> be here.

No, I don't think so.

With CONFIG_FRAME_POINTER %rbp is being saved and restored, so there is no
problem in case the seamcall is clobbering it.


Juergen

> > +		pr_err("Too old version of TDX module. Consider upgrade.\n");
> > +		ret = -EOPNOTSUPP;
> > +		goto error_out;
> > +	}
> > +
> >   	return 0;
> >

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